Gui is the tenth and last of the Heavenly Stems (tiangan). Its element is Water and its polarity is yin, so Gui is glossed as yin Water, likened in tradition to rain, dew, or mist, gentle and pervasive where the yang Water of Ren is the sea. As the final stem it pairs with the twelve Earthly Branches to complete the pattern of the sexagenary cycle of sixty; after Gui the count of stems returns to Jia. Each of the five phases appears among the ten stems once as yang and once as yin, and Gui carries the yin aspect of Water that closes the round. These are the conventions of the Chinese calendrical and cosmological tradition, drawn on in the almanac and in the four-pillars art of fate calculation.
Gui is the tenth and final Heavenly Stem, paired with Ren under the Water phase but carrying the Yin polarity, likened to rain, mist or a quiet spring rather than Ren's ocean, gentle and pervasive rather than forceful. As an even-numbered stem, Gui combines only with the six Yin Earthly Branches, Ox, Rabbit, Snake, Goat, Rooster and Pig, closing out the sixty-term sexagenary cycle before it returns to Jia at position one. Because ten stems and twelve branches share a lowest common multiple of sixty, a complete Jia-to-Gui, Zi-to-Hai cycle takes sixty years, months, days or hours to repeat exactly, which is why traditional East Asian reckoning treats sixty years as a full cycle of a human life, marked in some communities by a huanjia or sixtieth-birthday celebration. In four pillars (BaZi) astrology a Gui day master is read as intuitive, adaptable and reflective, the most yielding of the ten stems.